In the present study, novel copper-doped zirconium-based MOF (UIO-66) and copper-doped iron-based UIO-66 catalysts were prepared by hydrothermal synthesis method to improve the removal performance of gaseous benzene. The characteristics of the catalysts were analyzed by means of XRD, SEM, XPS, BET, and EPR. The copper loading catalyst had high crystallinity and irregular globular. The three kinds of catalysts with different Cu/Fe ratios had regular cubic shape. Compared with the catalyst supported with single copper, the bimetal Cu/Fe modification had a certain adjustment effect on the morphology, which specifically reflected in the uniform size and shape of catalyst particles with better dispersibility. The factors of different metal loading, dose of H2O2, and reaction temperature on benzene removal have been studied. It has been observed that in heterogeneous advanced oxidation removal of benzene, 3-Cu@UIO-66 and Cu1.5/Fe1.5@UIO-66 achieved the highest benzene removal efficiency of 81.2% and 94.6%, respectively. EPR results showed that the increase of Cu loading and different Cu/Fe ratios promoted the yield of hydroxyl radicals, thus promoted the benzene removal efficiency. The efficiency of heterogeneous oxidation removal of benzene first increased and then decreased with the increase of temperature due to H2O2 instability. DFT calculations exhibited that the Feoct-Cu-O site was a more effective activation site than the single Feoct-O site. Dissociative adsorption occurred with the O-O bond of H2O2 cracked, and the formed hydroxyls parallel adsorbed on the benzene surface. The combination of benzene and hydroxyls was strong chemisorption with the torsion angle of benzene ring obviously turned. The work was of great importance for identifying the roles of the novel catalyst for the removal of benzene pollutant from waste gases.
Keywords: Benzene; Cu/Fe bimetallic oxide; Hydroxyl radical; Removal; UIO-66.
© 2023. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.